At the Evangelical Alliance, we often hear from those outside the evangelical Christian community with strong – if not always accurate – opinions on who we are. The impression people sometimes have of us as rightwing fundamentalists does not reflect the vast diversity of opinions we hear from within our two million strong community. British evangelicals encompass a wide variety of political views, but there is one characteristic you can count on when trying to spot one – a commitment to the Bible.

This commitment is one of the four fundamental markers identified by David Bebbington, professor of history at Stirling University, in his monumental history of British evangelicalism. The others are a focus on Jesus' death on the cross, an emphasis on personal conversion, and an activist spirit. Given that we are defined by this reverent respect for the Bible, it seems fairly sensible to actually draw on the biblical text in order to answer the question: "What should evangelicals believe?"

I will do this by focussing on what has come to be known as Jesus' "Sermon on the Mount", recorded in the gospel of Matthew, chapters five to seven. This seems particularly pertinent not just because in it Jesus sets out to some extent a manifesto for his followers, but also because it has driven the four criteria that Bebbington comes to identify. Jesus begins with the so-called "beatitudes", a series of statements that challenge some of the received wisdom of his day. For instance, according to Jesus, it is the meek, not the strong or mighty, that will inherit the earth. He goes on to indicate that the task of believers is to change the world around them, though, interestingly, he does not highlight at this point our preaching but rather our "good deeds" as that which will lead to those around us giving praise to God.

Perhaps with that sentiment in mind, Jesus goes on to deepen his hearers understanding of the purpose of the Old Testament law. In his repeated refrain, "you have heard that it was said, but I say to you", Jesus encourages his followers to view obedience not merely in terms of outward conformity, but much more importantly in terms of a renewed heart and spirit within. So, adultery is not merely a matter of the physical act, but also a state of mind. In saying this, Jesus is clear he is not as such negating the Old Testament law, but he is encouraging his readers to read it more deeply. Hence, Jesus can say that the Old Testament command to love your neighbour now applies equally to loving your enemies, which given that Palestine was under Roman occupation at the time is the equivalent of telling the residents of Mosul to love the US marines. And in its recent "Don't be a Stranger" campaign, the Evangelical Alliance has sought to build on this teaching to encourage a more loving response to migrants within our communities.

Jesus continues by addressing a range of religious behaviours – prayer, fasting and giving to the needy. He enjoins his followers to avoid judgmentalism, to discern the right path and right teaching, and to act with integrity. But then he concludes with the well-known story of the wise and foolish builders. The point of the story is not so much that we must build our lives upon his teaching, but that our lives must be built on our obedient response to his teaching. So, he says:

Therefore everyone who hears these words of mine and puts them into practice is like a wise man who built his house on the rock.

It strikes me, then, that if evangelicals are going to claim to be followers of Jesus Christ – which is what we do claim – then perhaps the question we need to be asking is not just "What should evangelicals believe?" but perhaps more importantly "How should we behave?" In The Way of All Flesh, Samuel Butler, the 19th Century novelist, famously wrote in regard to a congregation that valued the status quo of formal religion that, "they would have been equally horrified at hearing the Christian religion doubted, and at seeing it practiced." Sadly, I sometimes wonder if the same could be said of evangelical Christians. For in his ethic of outrageous love, championing of the poor and freedom from hypocrisy, Jesus' words continue to test evangelicalism at its heart – and I say this as one who sits at the centre of the British movement. The fact is, we may believe his words, but obedience to them remains a distinct challenge for each one of us.